A professor finds that the average SAT score among all students attending his college is 1150±150 (?±?). He polls his class of 25 students and finds that the average SAT score is 1200. Suppose he computes a one-independent sample z-test at a .05 level of significance. What is his decision?

A. to reject the nullhypothesis

B. to retain the null hypothesis

C. to reject the null hypothesis for a two-tailed test, but to retain the null hypothesis for an upper-tailed test

D. to reject the null hypothesis for an upper-tailed test, but to retain the null hypothesis for a two-tailed test